1. Field of the Invention
The present invention relates to a display apparatus and a display method.
2. Description of the Related Art
Conventionally, an automatic control method of a phase of a quantization clock (which may also be referred to as a “quantization phase” hereinafter) is known and used for a quantization of an analog video signal input from a computer to a display apparatus.
For example, Japanese Patent Laid-Open No. (“JP”) 11-177847 discloses a method of adjusting a phase of a quantization clock so that the phase can maximize a differential absolute value between more than one adjacent image data in image data obtained by quantizing an input video signal of one frame with the quantization clock. JP 2000-347615 discloses a method of adjusting a phase of a quantization clock configured to maximize a video signal value (first embodiment) or a differential absolute value (second embodiment). Other prior art include JP 11-167371.
JP 11-177847 is effective to an image in which a slope of a variation of a video signal level usually inverts for each pixel (as in FIG. 2 of JP 2000-347615), but the phase is unavailable in other cases (such as FIG. 4 of JP 2000-347615).
JP 2000-347615 utilizes a maximum value of a video signal value in the former case, and a maximum value of a differential absolute value in the latter case. However, JP 2000-347615 assumes a signal having a reset potential as an input signal in the former case, and cannot be applied to an output signal from a computer. In addition, a differential absolute value between two adjacent pixels in JP 2000-347615 is subject to the noises and the quantizing precision is likely to decrease.